The present invention relates generally to electronic image capturing devices, and more particularly to lens cap detection for an image capturing device with a movable lens.
Image capturing devices are used to visually memorialize scenes, events, or items. A common image capturing device is a camera. Cameras include both still and video cameras, and may capture images using either analog or digital technology. They commonly use a lens apparatus to admit light reflected from the image of interest and focus it onto some sort of image capturing apparatus, such as a CCD array or a photosensitive film. The lens apparatus is therefore a critical component of the camera, and must be protected from damage in order to maintain image quality.
Most modern cameras include a processor and/or other control electronics that function to control shutter speed, aperture, flash, focus, etc. In addition, a camera may include one or more user input devices that allows a user to turn the camera on and off, select settings, capture images, select flashes, zoom in or out, etc.
The lens in a camera may be movable, and is typically extended upon power-up of the camera. A first type of movable lens is a lens or lens device that retracts at least partially into the camera body. This may be done in order to protect the lens and minimize the size of the camera when not in use. Another type of movable lens is a zoom lens, through which the user may change the focal depth of the camera. A camera having a zoom lens may additionally retract the zoom lens when going into a power-down state.
Because the lens is an expensive optical instrument that must be protected, most cameras employ some form of lens cover that fits over the lens to keep out dust and prevent the lens from getting scratched or damaged. However, in many cameras having a movable lens, the lens apparatus is typically moved to a default position upon power up, i.e., when the user turns the camera on. If the lens cap is not removed prior to the power up and extension of the lens device, the lens drive motor could be damaged. In addition, the lens may contact the lens cap and damage the lens. Furthermore, the blocked zoom lens may draw excessive current, which will shorten battery life. Finally, pictures cannot be taken with the lens cap on.
The prior art approach to this problem is simply to leave it to the user to remember to remove the lens cap prior to turning on the camera to a powered-up state. However, because of the high level of automation in modern cameras, this is unacceptable for the reasons explained above.
Therefore, there remains a need in the art for improvements in image capturing devices having movable lenses.
A lens cap detection system for an image capturing device is provided according to one preferred embodiment of the invention. The lens cap detection system comprises a lens apparatus and a lens cap detector that is capable of detecting the presence of a lens cap on the lens apparatus and outputting a signal indicative thereof. The lens cap detection system further includes a processor that communicates with the lens cap detector. The processor generates an alert if the lens cap is detected by the lens cap detector, and does not generate an alert if the lens cap is not detected.
According to another embodiment of the invention, the lens cap detection system comprises an electronic imaging device lens cap detector that measures a level of light received in the image capturing device through the movable lens apparatus and generates a light level measurement. The lens cap detection system further comprises a memory storing a predetermined light threshold value. The lens cap detection system further comprises a processor that receives a light level measurement from the electronic imaging device lens cap detector, compares the light level measurement to the stored predetermined light threshold value, and controls the lens drive motor to extend the movable lens apparatus if the light level measurement is greater than the predetermined light threshold value. The processor controls the lens drive motor to remain inoperative if the light level measurement is less than or equal to the threshold.
According to yet another embodiment of the invention, a computer-implemented lens extension method for moving the lens of an image capturing device is provided. The method comprises the step of detecting a lens cap on a retracted movable lens apparatus of the image capturing device. The detection is performed by a lens cap detector and a processor of the image capturing device. The method further comprises the step of extending the movable lens apparatus if the lens cap is not detected and maintaining the movable lens apparatus in a retracted state if the lens cap is detected. The extending step of the movable lens apparatus is controlled by the processor.